1. Field of the Invention
The present invention relates to a fuse unit attached directly to a vehicle mounted battery, and having a fusible portion in supplying an electric power from the battery to the electric wire.
2. Related Art
FIGS. 10 and 11 show one form of the conventional fuse unit.
A fuse unit 101 connects a vehicle mounted battery with the electric wire for power supply, and comprises a plate-like fuse element 110 made of conductive metal having a fusible portion (not shown), and an insulating resin body 120 having the fuse element 110 insert molded.
As shown in FIG. 10, this resin body 120 is sprit into the front and rear divided bodies 121 and 122 which are extended in one-dimensional direction. Further, in use, the divided bodies 121 and 122 are bent like an L-character shape at an intermediate section, as shown in FIG. 11. Since the previous fuse unit bent like L-character shape at the time of molding takes a lot of time to perform the punching process, the conventional example facilitates the punching process and makes the resin body 120 bendable to solve this problem.
Both the divided bodies 121 and 122 are bent like L-character shape by a locking mechanism constituted by an engaging projection 125 and an engagement groove 126 and fixed. The engaging projection 125 is formed to project from a side face wall 127 rearward of a front divided body 121 (to the left in FIG. 10), and the engagement groove 126 is provided on a side face wall 128 forward of a rear divided body 122 (to the right in FIG. 10). When the engaging projection 125 engages the engagement groove 126, both the divided bodies are maintained in the L-character bent form.
This fuse unit 101 is used in L-character bent form, because the fuse unit 101 can be restrained from increasing in size (total length) due to an increased set number of fusible portions (greater fuse circuit) to incorporate a more diverse or complex form of the circuit into a narrow space around a battery post.
The fuse element 110 is punched from one sheet of conductive metal plate, having integrally a flexible portion 111 in the intermediate section to be freely bendable in a direction of plate thickness from the flexible portion 111. The flexible portion 111 is disposed in a portion of a resin metal mold (not shown) into which a resin material is not injected, so that the flexible portion 111 is exposed outside the resin body 120.
The fusible portion serves to protect the electrical parts by melting when there is an overcurrent flowing, and is constituted by a metal chip of tin or lead alloy. The fusible portion is provided at each of both front and rear sides of the fuse element 110, and located within a space area (not shown) of the resin body 120 to be visible.
With this constitution, the resin body 120 can be molded integrally in a state where the fuse element 110 is expanded in plane, whereby there is no need of molding the resin body in the bent shape as conventionally performed, the punching direction is only met with the 180 degree direction, the metal mold is simplified with lower cost, and the fuse unit 101 of complex shape can be easily molded.
However, when the divided bodies 121 and 122 that are sprit forward and rearward were bent around the flexible portion 111 of the fuse element 110 as the center of rotation, they might be bent excessively because there was no stopper for restricting the bending, bringing about the risk that the divided bodies 121 and 122 were unlocked. Additionally, there was a problem that due to a spring back of the rear divided body 122 tending to return, the divided bodies were unlocked and not maintained in the L-character bent form. This is because the flexible portion 111 is formed in smaller thickness to be easily bendable and have insufficient strength, and is likely to deform due to an external force, whereby the divided bodies can not be maintained in the L-character bent form only by the flexible portion 111.
Further, if the divided bodies are not maintained in L-character bent form, it is permitted to fit smoothly a partner connector (not shown) into a connector housing 123 of the rear divided body 122 vertically stood along the side wall surface of the battery, causing a risk of interfering with the outside from the narrow space around the battery.
The present invention has been achieved in the light of the above-mentioned problems, and it is an object of the invention to provide a fuse unit that has improved reliability of locking mechanism for the fuse unit and is maintained in the L-character bent form.
In order to accomplish the above object, according to one aspect of the present invention, there is provided a fuse unit comprising an electrically conductive fuse element having a plurality of fusible portions and formed with a flexible portion in an intermediate section, and a resin body containing the fuse element, the resin body being divided into a first divided body and the second divided body at the boundary of the flexible portion, the first divided body and the second divided body being bendable, characterized in that a restricting wall confronting an inner face wall of the first divided body is stood on an inner face wall of the second divided body.
With this constitution, the restricting wall stood on the second divided body makes contact with the inner face wall of first divided body that is the partner, thereby acting as a stopper wall against an external force in a bending direction, when both the divided bodies are bent.
In the fuse unit, the restricting wall may be provided with an inclined wall surface inclined in a direction away from the inner face wall of the first divided body.
With this constitution, if the restricting wall is provided with the inclined wall surface, the divided bodies can be bent over 90 degrees in locking, and maintained in the L-character bent form without causing a spring back, after locking.
In the fuse unit, the first divided body may be provided with a flexible arm having a latch, and the restricting wall of the second divided body may be provided with a notched wall portion, wherein a first locking mechanism may be constituted by the flexible arm and the notched wall portion.
With this constitution, if the locking mechanism is constituted by the flexible arm having the latch and the notch, the flexible arm is inserted through an opening of the notch, when the divided bodies in one dimensional direction are bent to be disposed in an orthogonal direction, whereby the divided bodies are bent in L-character form and completely locked.
In the fuse unit, the first divided body may be provided with an engaging projection, and the second divided body may be provided with an engagement groove that is engaged by the engaging projection, wherein a second locking mechanism may be constituted by the engaging projection and the engagement groove.
With this constitution, if the second locking mechanism is constituted by the engaging projection and the engagement groove, the engaging projection and the engagement groove are engaged, when the divided bodies are bent, so that the fuse unit is locked without rattling and the divided bodies are maintained in the L-character bent form.
In the fuse unit, the flexible arm may be provided on the inner face wall of the first divided body, the engaging projection may be provided on a side face wall of the first divided body, and the engagement groove may be provided on an extension wall from the side face wall of the second divided body.
With this constitution, the flexible arm provided on the first divided body is inserted through an opening into the notch of the second divided body, when the divided bodies are bent, so that both the divided bodies are bent in the L-character form to effect the first lock. At the same time, the engaging projection provided on the side face wall of the one resin body engages the engagement groove on the extension wall from the second divided body, thereby effecting the second lock. Since the extension wall has the flexibility, the second lock is not released abruptly.
In the fuse unit, the flexible arm may be located closer to the flexible portion, and disposed in the center of the inner face wall of the first divided body.
With this constitution, the flexural rigidity of the restricting wall can be prevented from being decreased without forming the restricting wall having the notched wall portion engaged by the flexible arm at great height. Also, when an abrupt external force is applied on the fuse unit of the L-character bent form in the expanding direction, the external force is distributed uniformly on the latch of the flexible arm, thereby preventing the lock from being released.
In the fuse unit, the notched wall portion may be formed to be thicker than the wall thickness of the restricting wall.
With this constitution, the strength of the notched wall portion is increased, and the plastic deformation is prevented, whereby the latch of the flexible arm is prevented from getting out of the notch, even if an abrupt external force is applied in the expanding direction.
In the fuse unit, a tipping-resistant rib may be provided at both ends of the restricting wall.
With this constitution, since the tipping-resistant rib is provided, the flexural rigidity of the restricting wall is increased, whereby when the fuse unit is bent excessively over a desired bending angle or an abrupt external force is exerted in the bending direction, the restricting wall is prevented from being deformed against the external force.